The invention relates to the pressure treatment of metals. In particular, the invention relates to manufacturing of different types of wheels, including wheels for vehicles, for automobiles, and aircraft, as well as rollers for the crawler-belt vehicles.
One known method for manufacturing of wheels utilizes die casting. This method exhibits high productivity and low cost. It provides for reliable operation of wheels so produced when the wheels are used on high quality roads, such as roads with a hard coating. However, mechanical properties of the alloys with a die cast structure are not adequate for wheels used on roads with coatings of poor quality, in sports cars, and heavy-weight vehicles. In addition, alloys with the die cast structure have a lesser specific strength as compared to alloys with a deformed structure. Therefore, wheels made by a die casting method typically are heavier than wheels made by forging.
Another known method for manufacturing of wheels utilizes forging. According to this forging method, a wheel is produced in several steps. The first step involves fabrication of a wheel block by forging. The central part of the wheel block comprises a hub, web, and a part of the rim having a collar. Another part of the wheel block comprises an initially-formed rim that comprises a cylindrical shoulder. The volume of the shoulder is generally equal to or more than the volume of the rim of the finished wheel. In a next step of a forging manufacturing process, a rim is rolled onto a mandrel. The final step using a forging process involves a calibration of the rim.
However, this method of the manufacturing using a forging method has limited applicability because the initial wheel block has to be of a specific design (configuration). Also, the conditions for hot rolling are not optimized by considering structure and mechanical properties of the initial wheel block. These disadvantages limit the process yield and lead to large amounts of metal scrap. For example, when hot rolling is applied to a wheel""s cylindrical part with a diameter that is generally equal to the diameter of the mandrel, the unrolled part of the rim is constantly displaced. In addition, a surface, which contacts with the mandrel, is subjected to the friction forces, and thus, the hot rolling based requires additional equipment capacity and requirements. It is necessary that the equipment decrease the speed of hot rolling, and allow additional stock to be added to avoid creation of necks (zones with smaller thickness) in rolled or intermediate parts of the wheel. Also, it is necessary that an additional calibration step, in conjunction with other steps in this method, be used in the process to solve the associated problems. The additional calibration steps increase the manufacturing time for wheel production, and adds to labor costs. Further, the additional calibration steps typically lead to an increased metal consumption, which is caused by a difficulty of the calibration of a wheel solely by means of a local metal redistribution. For example, thinning and thickening of certain wheel regions leads to displacement of metal portions beyond the formed wheel profile, similar to a flash during an open forging.
These and other aspects, advantages and salient features of the invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention.